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Herb extracts wrap up lethal food bugs

Basil, one of the mainstays of Italian cuisine, might one day become a weapon in the battle against dangerous food bugs such as E. coli and listeria.

A new plastic food wrapper for meat and cheese which slowly oozes anti-microbial chemicals extracted from the herb has been shown to increase the food’s shelf life, and should also cut the risk of food poisoning. And it does not taint the food with basil flavour, either.

Preliminary tests on the new wrapping show it keeps bacteria at bay in Cheddar cheese for a week longer than ordinary packaging. The finding was announced last week at a packaging research meeting in Spain by scientists at the Technion Institute of Technology in Haifa, Israel, and the Victoria University in Melbourne, Australia.

“The wrapper demonstrates a positive anti-microbial effect against the bacteria that are of particular concern when packaging cheese,” says Joseph Miltz, the group’s lead researcher.

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Attack and destroy

The plastic is laced with two chemicals extracted from basil&colon; an ether called methyl chavicol and the alcohol linalool. These are both known to be active against eight types of bacteria, including E. coli 0157 and listeria. Both organic molecules contain chemical groups that attack and destroy cell walls.

E. coli cases in the UK

The idea is to design the polymer mix so that each anti-microbial molecule binds fast to the plastic while remaining able to diffuse into the food. It is the water in the food that lures the molecules away from the polymer.

The wrapper would be most efficient if the volatile compounds diffused out of the polymer only towards the inside of the package, and not the outside. Miltz envisions using layered polymers to achieve this – with tougher, less permeable ones on the outside.

Potent horseradish

In Japan, the potent horseradish, wasabi, has been incorporated into packaging because of its anti-microbial activity, but people complained that it also flavours the food.

Although methyl chavicol and linalool impart taste at high concentrations, Miltz is using far lower levels and could not taste basil-like flavours in the cheese. The basil extracts are less soluble in water than wasabi and so do not adhere to the food as much, he adds.

Miltz says his anti-bacterial film is likely to be attractive to some consumers because the active chemicals come from a natural source, and are therefore less likely to degrade into harmful by-products.

Joseph Hotchkiss at the Department of Food Science at Cornell University in New York agrees that the “natural” origins of the chemicals are likely to be a selling point, but points out that this does not necessarily make them safer than artificial additives.